Curious as to your table storage params

Question

Hi everyone, I'm a long time Oracle guy, first time poster to these forums! I'm just curious as to your table storage parameters. For instance, do you use settings such as initial 128k next 128k pctincrease 0 for production tables after analysis? Or do you crank those settings way up, even "past" your projected usage? Anyone using megabytes for their table extents, such as inital 100M next 50M ? Or is that considered bad practice to project 10-15 years into the future?
Basically I'm re-doing the storage structure of the database that our 3rd party supplier set up; they set everything up with 32k initial extents, 8k subsequents, 121 max extents. (Sounds like Oracle 7!) Since that gives us only a meg of storage in a 2 GB table space, I'm currently analyzing our sample data to see what our requirements will be.
Actually does anyone mess with kilobyte extents anymore? Or do you go right to megabyte extents?
Thanks!
-Thomas H

Answer 1

Thomas:
It has always been best practice to size your objects appropriately, and to take all possible steps to ensure that tablespaces do not become fragmented. With LMTs, it is just that much easier, because users cannot violate the storage parameters you set up at the tablespace level.
With DMTs, a user can specify storage parameters that differ from the tablespace defaults and screw up your carefull analysis. with LMTs, any user supplied storage parameters are effectively ignored (well, they impact the number of extents initially allocated to the object, but not the size of those extents).
That said, I would do at least some minimal analysis of the space required for each of the tables and indexes. If, like most OLTP databases, you have a wide variety of object sizes, you can somewhat optimize the disk usage by keeping like sized objects together in one tablespace.
For example, in one (payroll/HR) application I support we have 3 LMT tablespaces, small, medium, and large.
Small holds the hundreds of small (2 - ~1,000 rows) lookup tables and their indexes, and has uniform extents of 64K
Medium holds the dozens of larger tables like employee demographics, job history etc. (~1,000 - ~1,000,000 rows) and indexes on those tables, and some of the large tables and has uniform extents of 5M.
Large holds the 5 or 6 extremely large tables like the detailed daily pay history (> 45,000,000 rows) and some of their larger indexes. This has uniform extents of 100M.
HTh
John